davidthings
Member
Simplified QuadDecode
Many thanks to TLB (OP) for this very helpful library.
My application is only a single revolution, so the 64K position counter restriction is no problem. In addition I will always need both decoders. These two relaxations of the requirements mean that the original code can be simplified dramatically. TLB saved me days of work with the original code, so I present my simplification in the hope that there might be others who need a simplified version.
I attach my simple of QuadDecode. No templates, no interrupts, header only.
Connect the encoders in the same way:
Encoder 1 - PhaseA pin 3, PhaseB pin 4.
Encoder 2 - Phase A pad 32, Phase B pad 25. (On the underside of the board)
Following TLB, I have left the Kinetis weak pulldowns activated. If you need pullups, tweak the PORTx_PCRn registers in lines 101-108 of the QuadDecode.h file.
Here's the demo. Comments / corrections welcome.
For fun, and to wrap up, here's the whole QuadDecode.h file
Many thanks to TLB (OP) for this very helpful library.
My application is only a single revolution, so the 64K position counter restriction is no problem. In addition I will always need both decoders. These two relaxations of the requirements mean that the original code can be simplified dramatically. TLB saved me days of work with the original code, so I present my simplification in the hope that there might be others who need a simplified version.
I attach my simple of QuadDecode. No templates, no interrupts, header only.
Connect the encoders in the same way:
Encoder 1 - PhaseA pin 3, PhaseB pin 4.
Encoder 2 - Phase A pad 32, Phase B pad 25. (On the underside of the board)
Following TLB, I have left the Kinetis weak pulldowns activated. If you need pullups, tweak the PORTx_PCRn registers in lines 101-108 of the QuadDecode.h file.
Here's the demo. Comments / corrections welcome.
Code:
#include <QuadDecode.h>
void setup() {
Serial.begin(115200);
}
int16_t Count1;
int16_t Count2;
void loop() {
int16_t c1 = QuadDecode.getCounter1();
if ( c1 != Count1 ) {
Serial.printf( " 1:%d\n", c1 );
Count1 = c1;
}
int16_t c2 = QuadDecode.getCounter2();
if ( c2 != Count2 ) {
Serial.printf( " 2:%d\n", c2 );
Count2 = c2;
}
}For fun, and to wrap up, here's the whole QuadDecode.h file
Code:
#ifndef QUADDECODE_H
#define QUADDECODE_H
#include <stdint.h>
#include "mk20dx128.h"
#include "core_pins.h"
/*
* Code simplified (and functionality reduced) from tlb's excellent code announced and discussed here
* https://forum.pjrc.com/threads/26803-Hardware-Quadrature-Code-for-Teensy-3-x
* Changes:
* - removed >64k irq code
* - untemplated into a single monolith
*
* HARDWARE DETAILS
* Teensy ARM
* ENCXA 3 PTA12 28 Input FTM1 7
* ENCXB 4 PTA13 29 Input FTM1 7
* ENCYA 32 PTB18 41 Input FTM2 6
* ENCYB 25 PTB19 42 Input FTM2 6
*
* KINETIS REGISTERS
* PORTx_PCRn
* Bit 10-8 MUX - function Multiplexor (0 = Disabled - Analog) See P223 of Manual
* Bit 4 PFE - Passive Filter Enable
* Bit 1 PE - Pull Enable
* Bit 0 PS - Pull Select 0 - Down, 1 - Up
* 0x00000712 = Alt7-QD_FTM1,FilterEnable,Pulldown
*
* FTM1_CNT Counter value
* Bit 15-0 is counter value
* Writing any value updates counter with CNTIN
* FTM1_MOD Modulo (Max value)
* Bit 15-0 is counter value - set to 0xFFFF
* Write to CNT first
* FTM1_MODE Features Mode Selection
* Bit0 FTMEN FTM Enable - [WPDIS must be 1 to write]
* Bit2 WPDIS Write Protect to Disable
* Set WPDIS, then set FTMEN - must be set to access FTM regs
* FTM1_FMS Fault Mode Status
* Bit 6 WPEN Write Protect Enable
* Write 1 to clear WPDIS
* FTM1_FILTER
* Filter out pulses shorter than CHxFVALx 4 system clocks
* Bit 7-4 CH1FVAL for PHB
* Bit 3-0 CH0FVAL for PHA
* FTM1_QDCTRL Quadrature Decoder Control and Status
* Bit 7 PHAFLTREN Phase A Filter Enable
* Bit 6 PHBFLTREN Phase B Filter Enable
* Bit 5 PHAPOL Phase A Polarity
* Bit 4 PHBPOL Phase B Polarity
* Bit 3 QUADMODE Quadrature Decoder Mode
* 0 for Quadrature
* Bit 2 QUADIR Counting Direction
* Bit 1 TOFDIR Timer Overflow Dir
* 0 was set on bottom of counting
* 1 was set on top of counting
* Bit 0 QUADEN Quadrature Mode Enable
* 1 is quadrature mode enabled [WPDIS to write]
* FTM1_SC FTM1 Status and Control
* Bit 7 TOF Timer Overflow Flag
* Bit 6 TOIE Timer Overflow Interrupt Enable
* Bit 5 CPWMS Center Aligned PWM Select
* Resets to 0 (Write when WPDIS is 1)
* Rest of bits are 0 (Write when WPDIS is 1)
* FTM1_C0SC FTM1 Channel 0 Status and Control
* Set WPDIS before writing control bits
* Bit 7 CHF Channel Flag
* Channel event occured
* Read and write 0 to clear
* Bit 6 CHIE Channel Interrupt Enable
* Set for compare interrupt
* Bit 5 MSB Channel Mode Select B
* Set to 0
* Bit 4 MSA Channel Mode Select A
* Set to 1
* Bit 3:2 ELS Edge or Level Select
* Set to 0:0
* FTM1_COMBINE
* Set WPDIS to 1 before writing
* DECAPEN (Dual Edge Capture Enable)
* COMBINE (Combine Channels)
* Resets to all zero
* FTM1_C0V Channel 0 Value
* Channel Compare Value
* Set to 0x80 - halfway thru count
* FTM1_STATUS
* Duplicate of CHnF bit for all channels
* Bit 0 CH0F
*/
class QuadDecode_t {
public:
QuadDecode_t() {
// Pin Assignments
// FTM1 Pins
// K20 pin 28,29
// Bit 8-10 is Alt Assignment
PORTA_PCR12 = 0x00000712; //Alt7-QD_FTM1,FilterEnable,Pulldown
PORTA_PCR13 = 0x00000712; //Alt7-QD_FTM1,FilterEnable,Pulldown
// FTM2 Pins
// K20 pin 41,42
// Bit 8-10 is Alt Assignment
PORTB_PCR18 = 0x00000612; //Alt6-QD_FTM2,FilterEnable,Pulldown
PORTB_PCR19 = 0x00000612; //Alt6-QD_FTM2,FilterEnable,Pulldown
//Set FTMEN to be able to write registers
FTM1_MODE=0x04; // Write protect disable - reset value
FTM1_MODE=0x05; // Set FTM Enable
FTM2_MODE=0x04; // Write protect disable - reset value
FTM2_MODE=0x05; // Set FTM Enable
// Set registers written in pins_teensy.c back to default
FTM1_CNT = 0;
FTM1_MOD = 0;
FTM1_C0SC =0;
FTM1_C1SC =0;
FTM1_SC = 0;
FTM2_CNT = 0;
FTM2_MOD = 0;
FTM2_C0SC =0;
FTM2_C1SC =0;
FTM2_SC = 0;
// Set registers to count quadrature
FTM1_FILTER=0x22; // 2x4 clock filters on both channels
FTM1_CNTIN=0;
FTM1_MOD=0xFFFF; // Maximum value of counter
FTM1_CNT=0; // Updates counter with CNTIN
FTM2_FILTER=0x22; // 2x4 clock filters on both channels
FTM2_CNTIN=0;
FTM2_MOD=0xFFFF; // Maximum value of counter
FTM2_CNT=0; // Updates counter with CNTIN
// Set Registers for output compare mode - for IRQ?
//FTM1_COMBINE=0; // Reset value, make sure
//FTM1_C0SC=0x10; // Bit 4 Channel Mode
//FTM1_C0V= COMP_LOW; // Initial Compare Interrupt Value
FTM1_QDCTRL=0b11000001; // Quadrature control
FTM2_QDCTRL=0b11000001; // Quadrature control
// Filter enabled, QUADEN set
// Write Protect Enable
FTM1_FMS=0x40; // Write Protect, WPDIS=1
FTM2_FMS=0x40; // Write Protect, WPDIS=1
}
void setCounter1( int16_t c ) {
FTM1_CNT = c;
}
void setCounter2( int16_t c ) {
FTM2_CNT = c;
}
int16_t getCounter1( ) {
int16_t c = FTM1_CNT;
return c;
}
int16_t getCounter2( ) {
int16_t c = FTM2_CNT;
return c;
}
};
QuadDecode_t QuadDecode;
#endif
